The present invention concerns an airborne basket structure for workmen for suspension from an elevated support such as a hovering helicopter.
Power transmission lines of the high voltage type transmitting power between power sources and substations are typically supported at intervals by towers spaced along a right-of-way. Also intermediate each of the towers is a static line (or lines) which serves in the general purpose of a lightning rod. Such a static line is spaced several feet above the power transmission line.
Such static lines are spliced at intervals and must be periodically inspected and serviced which constitutes a problem in that such lines are commonly located over cultivated land which results in both land and crop damage when truck supported cranes, etc., are used. The lines often pass over right-of-ways which are subject to environmental restrictions. Further, the use of cranes and the like is inefficient from a time standpoint by reason of the vehicle having to negotiate a wide variety of terrain and indirect routes between work sites. A further drawback to the use of ground supported equipment is the risk of serious injury or death by accidental contact with the high voltage transmission lines located below the static lines. Heretofore, to avoid such risk, the power transmission lines were de-energized at considerable cost and effort. Line location at 100 feet or so above the ground further complicated the use of ground equipment.
In the prior art, to the extent known, U.S. Pat. No. 3,863,736 discloses a workmen supporting scaffold for air-lifting by a helicopter into temporary placement atop a column supporting power transmission and static lines. The airlifted scaffold is suspended below the helicopter and upon lowering of the latter downwardly inclined arms on the scaffold engage column crossarms coming to rest thereon with the scaffold lower portion in abutment with a subjacent portion of the column. Subsequent to platform placement on the column, the scaffold is detached from the helicopter and the helicopter reorientated so as to permit discharge of workmen onto a platform surface. The disclosed scaffold is not intended for nor capable of suitable engagement with a static line nor was such use apparently ever envisioned for same.